Balloon catheters may be used to deliver drugs to tissue at a desired location of a body lumen or cavity. Typically, the balloon is positioned at the desired location for drug delivery by sliding it through portions of the body lumen or cavity where no drug delivery is desired. Consequently, it may be difficult to avoid undesired drug release during the positioning of the balloon, particularly when the body lumen or cavity transports bodily fluids into which the drug may be released.
U.S. Pat. No. 5,304,121 describes a drug delivery system that uses a hydrogel coating. The '121 patent discloses a rigid sheath member extendable over the hydrogel coating to help prevent the release of the drug into bodily fluids. The entire disclosure of the '121 patent is hereby incorporated herein by reference.